Pigments used for an electrophotographic toner (hereinafter, simply referred to as “toner” in some cases) generally have four colors including yellow, magenta, cyan, and black. However, in recent years, a high degree of decorativeness has been required for packaging, cards, and the like, and accordingly, pigments exhibiting a high degree of decorativeness are used in addition to the pigments of four colors. The pigments exhibiting a high degree of decorativeness show pearly luster, metallic luster, holographic luster, and the like. Among the pigments exhibiting a high degree of decorativeness, the pigment (also referred to as “pearl pigment”), which is obtained by covering a mica pigment showing pearly luster with fine metal oxide particles, is widely used since this pigment provides a strong metallic impression to an individual.
The pigment particles having a high degree of decorativeness generally have a large particle size. For example, the particle size of the pearl pigment particles is generally from about 5 μm to about 200 μm. The greater the particle size of pigment particles is, the higher the degree of glitteriness of the pigment particles. Moreover, the closer the shape of the pigment particles to a flat plate shape, the higher the degree of glitteriness of the pigment particles. In addition, during the formation of an image, if the flat surface of the flat plate pigment particles is disposed in parallel with the surface of the image, the degree of the glitteriness of the pigment particles is further enhanced.
In the field of related art, there is a technique relating to the formation of an electrophotographic image using a toner which utilizes highly decorative pigment particles having a large particle size. However, due to the following problems, the technique is not sufficiently reliable to be put to practical use.
Firstly, when a toner is produced using highly decorative pigment particles having a large particle size, the pigment may be crushed during the steps of kneading, grinding, and the like. Consequently, the particle size and shape of the pigment particles cannot be maintained, and glitteriness is not sufficiently exhibited thereby in some cases.
Secondly, even if the pigment particles have the shape of a flat plate, the toner image containing the pigment particles may not have the shape of a flat plate. Therefore, during the formation of an image, the surface of the tabular pigment particles is not disposed in parallel with the surface of the image, and the glitteriness is not sufficiently exhibited thereby.
Thirdly, the pigment particles are readily exposed on the surface of the toner containing the pigment particles. Consequently, the uniformity of chargeability among the toner particles may become insufficient, the toner may not be sufficiently fixed onto a medium during the formation of an image, and the member such as a photoreceptor in an image forming apparatus may be easily contaminated. Moreover, these problems may readily easily lead to image defect.